In accordance with the prior art, distance to a certain object may be measured using triangulation, interferometry, confocal chromatic, direct pulse type time of flight (ToF) or indirect phase type frequency modulation ToF. Indirect phase type frequency modulation ToF usually involves multiplying a detector signal with four separate reference phases. The distance may then be determined as
      D    =                  c        ·        phase                    4        ⁢        π        ⁢                                  ⁢        f              ,where c denotes the speed of light and f denotes the modulation frequency. The phase may be determined from the four digitally converted products a0 . . . a3 as
  phase  =            tan              -        1              ⁢                  {                                            a              0                        -                          a              1                                                          a              2                        -                          a              3                                      }            .      Consequently, four multipliers and ADC channels are required for computing the phase, which results in a relatively large digital area and high power consumption in a device for time of flight measurement.